The present invention relates to a magnetic disc unit having a thin film magnetic head mounted thereto, and more particularly to a magnetic disc unit capable of realizing high recording density.
In general, a thin film magnetic head has a small inductance and a large reproducing output obtained even for a high frequency, as compared with the prior art bulk type head employing a ferrite core and the like, and therefore, it is a device essential to the promotion of the high recording density of a magnetic disc unit. In recent years, since the promotion of the high coercive force of a recording medium as well as the promotion of the high recording density have been advanced in the magnetic disk unit, it is required for the thin film magnetic head to have a capability of sufficiently recording or reproducing information in or from the recording medium of high coercive force.
One example of the thin film magnetic head is disclosed in JP-A-60-35316 for example. The thin film magnetic head in which an upper magnetic substance is made of a material having larger saturation magnetic flux density than that of a material of a lower magnetic substance is disclosed in JP-A-60-35316 and JP-A-2-126410. The characteristics of the thin film magnetic head employing a magnetic material are disclosed in an article IEEE, TRANSACTIONS ON MAGNETICS, Vol. 25, No. 5 (1989), pp. 3212-3214 for example. The thin film magnetic head employing a magnetic core formed of a multilayer magnetic film in which a magnetic film and a non-magnetic film are alternately laminated is disclosed in JP-A-58-171709.